By Harold McGee
Lamb and sheep meat is finer grained and more tender than beef, but well endowed with red myoglobin and with flavor, including a characteristic odor that becomes more pronounced with age. Pasture-feeding, particularly on alfalfa and clover, increases the levels of a compound called skatole, which also contributes a barnyardy element to pork flavor, while lambs finished on grain for a month before slaughter are milder. In the United States, lambs are sold in a range of ages and weights, from 1 to 12 months and 20–100 lb/9–45 kg, under a variety of names, including “milk” and “hothouse” lamb for younger animals, “spring” and “Easter” lamb for the rest (though production is no longer truly seasonal). New Zealand lamb is pasture-fed but slaughtered at four months, younger than most American lamb, and remains mild. In France, older lambs (mouton) and young female sheep (brebis) are aged for a week or more after slaughter, and develop an especially rich flavor.